Apparatus for injection moulding plastic articles of different kinds, mainly (but not exclusively) everyday objects such as toothbrush bodies, writing utensils, handle parts, medical components or other plastic components of any kind, which are injection-moulded from a plurality of plastic components due to functional or design requirements, comprise a plurality of injection moulding stations.
Such apparatus generally have a mould block that is stationary on the nozzle side, on which mould block one, or a group of, sub-cavity/sub-cavities is/are formed for each component to be injection-moulded, a mould block that is movable on the ejection side, on which one, or corresponding groups of, sub-cavity/sub-cavities is/are formed, which in the case of a closed injection moulding apparatus form, together with the sub-cavities of the stationary mould block, cavities for injection moulding the articles, and an ejection station which is located outside of the mould blocks.
Between the groups of cavities and the ejection station, the moulded parts are transported by means of a mould block or a section of the mould block, namely a holder. The holders form, e.g. in the case of toothbrush bodies, so-called head inserts, which are inserted in recesses of the mould block on the ejection side and form sub-areas of the sub-cavities, which correspond to the head area of a toothbrush body. Tools of this kind are shown for example in DP 102 08 599 A1 or in DE 20 2006 017 919 U1. These holders are positioned by a drive mechanism having predetermined linear or rotary index steps from the first group of cavities to the next up to the ejection station and back again to the first group of cavities.
During the production of brushes, for example toothbrushes, household brushes or paintbrushes, it is customary to guide a brush body successively to various processing stations, including injection moulding stations, on each of which one specific processing step, amongst others at least one injection moulding step, is carried out. For example, the basic form of the brush body is injection-moulded in one injection moulding station, in a subsequent station a second component of a different colour and/or a different hardness is moulded onto it. In further stations, further components are moulded on top of it, or a small brush plate that has already been stuffed with bristles is overmoulded in order to produce the entire brush body with head, neck and handle. Yet further stations are feed or ejection stations.
In order to shift the already partially injection-moulded brush body by means of the holder and/or the complete mould block itself, one or more slides are used which circulate along a specified path, i.e. a specified guide, in such a way that they (possibly with the partially or completely injection-moulded articles) are presented one after the other to the various stations for processing. In a simple example, the injection moulding apparatus includes a loading station, one, however preferably a plurality of injection moulding stations, and an unloading station. After that, for example three or four slides may be used which are each indexed by one station at every cycle of the injection moulding apparatus.
On the or each slide, respectively one or several motors is/are attached, which generate individual movements. For example, there are injection moulding devices, in which each slide has its own motor provided for driving the slide along the guide. Moreover or alternatively, one or more motors may be provided on the slide, by means of which e.g. the holders for the partially or completely injection-moulded articles are shifted. The electrical power supply to the motors and the control to the motors is carried out via separate lines, namely via electrical power supply lines and signal lines. These lines lead to a stationary contact point, mostly to sliding contacts, in order to realise the transition from the movable to the stationary part. To ensure that the motors can be operated independently from each other, each motor has its own set of sliding contacts, which ensures the transition from the stationary line section to the moved line section.
It is the object of the invention to provide an injection moulding apparatus that is designed in a more cost-effective manner and requires less maintenance.